class Hashie::Dash

def initialize(attributes = {}, &block)

just like you would many other kinds of data objects.
You may initialize a Dash with an attributes hash 
def initialize(attributes = {}, &block)
  super(&block)
  self.class.defaults.each_pair do |prop, value|
    self[prop] = value
  end
  attributes.each_pair do |att, value|
    self[att] = value
  end if attributes
  assert_required_properties_set!
end